Comorbidities and Complications Unique to Surgical Patients
Core concepts
Surgical critical illness is shaped by preexisting disease and by procedure-specific complications. Candidates should understand how diabetes (stress hyperglycemia, impaired wound healing), chronic kidney disease (volume and electrolyte fragility, drug dosing), cirrhosis (coagulopathy that is rebalanced, encephalopathy, varices), obesity (airway difficulty, dosing by adjusted body weight, venous thromboembolism risk), and cardiac disease (perioperative ischemia, arrhythmia) alter ICU management.
Common surgical complications include anastomotic leak, intra-abdominal hypertension and abdominal compartment syndrome, surgical site infection, aspiration, delirium, and venous thromboembolism. Intra-abdominal hypertension is graded by bladder pressure; abdominal compartment syndrome causes organ dysfunction (oliguria, elevated airway pressures, hypotension) and requires decompression. Postoperative fever timing helps localize causes, and unexplained deterioration after surgery should prompt evaluation for leak, bleeding, or ischemia rather than reflex antibiotic escalation.
Traps
Questions test the misconception that cirrhotic coagulopathy requires routine correction, that obesity dosing equals actual body weight for all drugs, and that a normal lactate excludes anastomotic leak. Another trap is attributing delirium to pain medication without excluding hypoxia, sepsis, or withdrawal.
Worked rule of thumb
A patient on postoperative day 5 develops tachycardia, oliguria, and rising airway pressures after laparotomy. Measure bladder pressure; if elevated with new organ dysfunction, treat as abdominal compartment syndrome with decompression rather than assuming fluid overload. Rule: new organ dysfunction after surgery equals a search for a mechanical or septic complication.
Exam strategy
Link each comorbidity to the specific drug, dose, monitoring, or complication it changes, and always consider the surgical complication before the medical one.